Contact device for engaging vibratory member



March 22, 1966 K. R. WOOLLEY 3,

CONTACT DEVICE FOR ENGAGING VIBRATORY MEMBER Filed Sept. 19, 1963 Jll16 INVENTOR. kEN/VETH z WO0LLE Y /-//5 ZITTOENFVS United States Patent 3,242,296 CONTACT DEVICE FOR ENGAGING VIBRATORY MEMBER Kenneth R. Woolley, Xenia, Ohio, assignor to Ledex, Inc., Dayton, Ohio, at corporationof Ohio Filed Sept. 19, 1963, Ser. No. 310,008 7 Claims. '(Cl. 200-166) This invention relates to an improved reed contact and "more. particularly to a contact adapted .to engage cantilever supported vibratile I reed elements. tion is not necessarily so limited.

Resonant reed devices of thetype'improved'by'the present invention typically comprise a'ferromag'netic reed element supported in a varying magnetic field, 'suchasith'e held of asolenoid coil havingan alternating vbltage input, and a"contactmeanspositioned adjacentthe reed-to detect vibration 'of'th'e reed. Frequently thereed is supported as a cantilever and has a frequency of resonant vibrationdependent'uponzits length, mass,resiliency and other structural properties. The contact is spaced from the 'reed'so as "to engage the reed-only when theamplitude 'of reed vibrationi-is great, and more specifically only when the reed is in resonance with a signal frequency p'a'ssingfthrou'ghthe solenoid coil.

In the construction of resonant reed relays of this'type it has -been found thatthe construction of the contact which engageswhe reed'du'ring periods of res'onant reed vibration has animport'ant bearingJOn 't'he performance of the relay device. Ifthe contactisvtoofrigidlthe'vibrati'ngl reedtendsto' bounce err L'the contactr'and thevibratory motions of the reed become irregular and '.unpredictable. On the other 'hand,if the contact-is too flexible, 'thec'ontacttends to bounce "ofiYthefr'ee'd, 'iand'to vibrate independently'with the result thatzthe 'contactid'oes'notengage thawed at regular intervalsand "the signal produced by the relayidevice be-comesserratic.

'An object of the presenttinventioni is to provide anew and improved contact assembly for engaging" vibratile elements.

Another object ofthe present 'inventio'nis to provide a new and improved reed relay contact assembly having aprestre'ssed contact element.

"Still another object of thefprese'nt invention isto-provide'a new and improved reedrelayassembly having a -prestressecl contact elementwhich, uponengagementwith 'the vibratory reed of the relay device, isfdriven'to a position of increased stress.

"A'furth'er object of the 'prese'nt' invention is to provide a new and improved contact-assembly for use in reed relay devices, the contact assembly including a bias means whichVpre-stresse's the contact element'and the bias means, including means to guide'the contact element tOzaffiXd position for engagement Withthe vibratory reedof the relay device.

Other objects and advantages reside inthe construction 'ofpa1t's,the .combination'thereo'f, the method of 'manufacture'and themode of operation, aswilllbecome more apparent from-the-following description.

InFthe drawings:

FIGURE -1 is a longitudinalsectional view of a reed relay device embodying the; present invention.

FIGURE 2 is a transverse sectional view taken'substantially-along the line 22- of FIGURE 1.

FIGURE 3 is a plan view of a contact assembly employed in'the device of FIGURE 1.

However, the invenice FIGURE 4 is a side elevation view of the contact assembly of FIGURE 3.

FIGURE Sis a side elevation view illustrating a partial assembly of the contact assembly of FIGURE 3 and illustrating in phantom detail the distortion occurring in a spring Wire contact element upon completion of the contact assembly.

FIGURE 6 isa perspective view of a biasing spring employed in'the contact assembly of FIGURE 3.

Referring to the drawing in greater detail, reference numeral 10 designates a protective housing for the reed relay assembly, this housing being rectangular in cross section as illustrated in FIGURE 2. One end of the housing is enclosed with an annular metal plate 12 having an insulating plastic insert 14. The insert .14 supports prongs '16 which are adapted to fit into a conventional tube socket.

The opposite end of the housing 10 isenclosed by an insulating plate 18 having a circular recess20 in the interior surface thereof which receivesthe base of a spring wound spirally but convergently so as to have a conical shape. The spring 22 engages one end of an interior frame which supports the reed relay assembly. The 0pposite end of the frame 26 is supported by four coil springs '24, each of which makes electrical contact with oneof the prongs 16 and each of which seats in an insulating disc 45 at said opposite end of the frame 26. Only two of the four coil springs 24 appear in FIGURE 1, the other twosprings being located in the portion of the assembly .which has been removed to produce thesectional view illustrated.

The'frame 26 comprises two telescoping, hollow, cylindrical sections 28 and 30, bothsections being of metallic construction. An elongate reed 32 is disposed coaxially vwithin the sections 2 and 30 and secured at a central position to the interior of the end wall for the section 28 by soldering as illustrated at 34. The reed is thus supported as a cantilever. To provide the cantilever supported reed with a 'frequencyof resonance in the desired range, the 'reed may be undercut adjacent its fixed end as illustrated at 36, thereby increasing'the flexibility of the reed. As can be observed in FIGURE2, the reed isessentially rectangular in cross section.

Surrounding the reed 32 near, its free end is a solenoid coil 38 and adjacent the coil 38 is an annular permanent magnet 40 slip-fitted within the section 30 of the frame 26 and secured by-a suitable cement. Thesolenoid coil 38 is adapted to receivean electrical signal through conductors connected with twoof the springs 24 and two of the prongs 16. These conductors have been omitted from the drawingso as not to obscure the details therein.

The annular permanent magnet 40 has diametrically opposed north and south poles,these poles'being disposed opposite theflat surfaces of the reed 32. When an alternating voltage signal is-impressed upon the coil 38, 'the free end of the reed 32 alternately receives induced north and south magnetic polarities withthe result that the reed is alternately attracted to and repelled from the magnetic poles in the permanent magnet 40. When the frequency of the signal received by the coil 38 matches the natural resonant frequency of the reed '32, asdetermined by the undercut 36, the reed vibrates with large amplitude.

As is apparent from the foregoing description, the-reed relayvdevice illustrated has been suspended by means of springs in a supporting container, such that the reed relay device has been substantially isolated from external vibrations. Suspended reed relay devices of this type are especially useful in the mobile communications field, since they may be operated in moving vehicles without interference attributable to vibrations produced by the vehicle itself.

It is to be understood that the reed relay device of FIG- URE l merely illustrates one possible application for the present invention, which invention resides principally in the contact construction for the relay device. The description of this contact assembly, as associated with a reed relay device especially constructed for mobile applications, is not intended to limit the scope of applications for the present contact assembly in any manner.

Resonant vibration of the reed 32 is detected by means of the contact assembly designated generally by the reference numeral 50. This assembly includes an elongated, insulating plastic plate 52 having an aperture 53 adjacent one end thereof which receives a screw 54 threaded into the section 28 of the inner frame 26. As best seen in FIGURE 2, the section 28 has an axial slot 56 therein to receive the plate 52.

The plate 52 is adapted to support a spring wire contact 58, best seen in FIGURES 3 and 5. The wire of this contact is of a material suitable to the requirements of electrical contacts such as well known alloys of the platinum group. At one end the wire of the contact 58 is curved to form a hook 60 thereon, which is adapted to encircle the stem of a rivet 62, passed through an aperture 63 in the plate 52. As best seen in FIGURE 5, the contact 58, when relaxed, i.e., not stressed, has a portion 64 projecting outwardly from the hook 60, but remaining in the plane of the hook 60. Beyond the portion 64 the wire of the contact 58 is bent upwardly from the plane of the hook 60 to form a portion 66 which projects angularly upwardly from the plate 52. As best seen in FIGURE 3, the portion 66 connects to a laterally inclined portion 68, which in turn connects to a portion 69 disposed axially parallel to the portions 64 and 66. The portion 69 terminates with a reentrantly curved and upwardly projecting contact portion 70. The radius of curvature of this contact portion is deliberately sm-all'enough that the contact portion will not yield significantly or collapse under pressure from the vibrating reed 32.

As best seen in FIGURE 4, an annular spacer 80 overlies the hook 60 formed on the contact 58. Overlying the spacer 80 is a biasing spring member 72 having an aperture -74 therein for receiving the stem of the rivet 62. As best seen in FIGURE 6, the spring member 72 is generally flat and has a slight curvature along its longitudinal axis. The biasing spring terminates at the end opposite the aperture 74 with a flange 76 projecting outwardly from the convex side of the spring 72. The flange 76 has a V-shaped notch 78 formed therein adjacent one end thereof.

For assembly of the flat spring 72 on the plate 52, the spring 72 is laid over the spacer 80 with its concave surface opposite the plate 52. Then a spacer 82 is placed over the spring 72 and the rivet 62 sw-aged into position. The spacers 80 and 82 have a relatively large area of contact with the spring 72 and thereby curb any tendency of the spring to pivot about the stem of the rivet 62. The V-shaped notch in the spring 72 is so located with respect to the spring wire contact 58 that the laterally inclined portion 68 of the spring wire contact seats in the notch 78. The curvature of the spring 72 is such that with swaging of the rivet 62 into position, the spring wire contact 58 is pressed downwardly toward the plane of the plate 52. The resulting stressed condition of the spring wire contact is illustrated in phantom detail in FIGURE 5, and there it can be noted that the portion 66 of this contact has been forced to pivot downwardly, with the angular bend between the portions 64 and 66 acting as a fulcrum and with the result that the portion 64 is caused to arch upwardly a slight distance. While not clearly shown in the drawings, the pressure applied by swaging of the rivet may partially embed the hooked portion 60 of the spring wire contact 58 into the surface of the plastic plate 52.

For accurate positioning of the contact portion 70 of the spring wire contact 58, a threaded screw element 84 is fitted into a suitable, internally threaded aperture in the plastic plate 52 and advanced upwardly against the flat spring 72. By this device the flat spring 72 may be elevated so as to relieve the biasing pressure on the'spring contact 58 and thereby permit the contact portion 70 thereof to move upwardly from the plate 52. By adjustment 'of the screw 84 the contact portion 70 may therefore be advanced closer to the reed 32 or by reversal of the direction of rotation of the screw 84, backed away from the reed 32.

To satisfy the objectives of the present contact construction, it is desirable that the force constant of the spring 72 besubstantially greater than the force constant for the spring wire contact 58. Due to the fact that the spring 72 is a fiat and relatively broad member'as compared to the diameter of the spring wire in the contact 58, this condition is readily obtained.

To eliminate any tendency of the spring 72 to twist upon adjustment of the position thereof by the screw 84, it is desirable that this screw engage the spring 72 midway between t-he sides thereof, as shown in FIGURE 3. At the same time, for the particular structure illustrated, it is desirable that the contact portion 70 of the spring wire contact 58 be aligned centrally with respect to the sides of the plate 52. 'It is to satisfy both of these objectives that the springwire contact 58 is provided with the laterally inclined portion 68, which permits the portion 66 to pass to one side of the screw 84 while locating the contact portion 70 centrally with respect to the plate 52.

With the contact assembly positioned as illustrated in FIGURE 1, the contact portion 70 on the spring wire contact 58 is positioned adjacent the undercut portion of the reed 32, and the separation determined by the adjustment of the screw 84. Desirably the separation is great enough that random vibrations of the reed 32 induced by signal frequencies in the coil 38 outside the resonant frequency range are insuflicient in amplitude to permit the reed to engage the contact portion 70. The contact portion 70 is positioned close enough to the reed, however, that when a signal of the resonant reed frequency passes through the coil 38, causing the reed to vibrate at its resonant frequency, the reed will actually strike the contact portion 70. When this occurs the reed 32 moves the contact downwardly as viewed in FIGURE 1, i.e.,.in a direction of greater stress in the spring wire. Preferably, the force constant of this spring wire, even in its stressed condition is small enough in relation to the momentum of the reed during resonant vibration that the reed experiences no appreciable resistance upon engaging the contact element 58. As the reed returns upwardly, after reaching an extreme of downward movement in its resonant vibration, the spring wire contact 58 follows the reed upwardly until it reaches the notch 78 in the flange 76 of the flat spring 72. As the spring wire contact moves into this notch, the side walls of the notch guide the spring wire contact to a fixed position at the side wall juncture or apex of the notch 78, this juncture serving as an abutment for limiting further upward movement of the spring wire contact. Due to the fact that the walls of the notch 78 always return the spring wire contact to the same position, the contact and reed always engage at the same pointin each successive cycle of operation. To minimize disturbance to the reed movement, it is desirable that the point of engagement between the reed and the contact is substantially midway between the narrow sides of the reed.

To minimize the extent to which the pre-stressed spring wire contact 58 can interfere with the vibration of the reed 32, the contact assembly is placed relatively close tothe fixed end of the cantilever supported reed, and when the reedvhas been undercut as illustrated at 36, it is desirable that the contact portion 70 engage the reed in the vicinity of the undercut. This reduces the effect of contactpressure on the reed as compared to the magnetic signal. Thus, it is the magnet 40 which, in effect, drives the reed, and this driving force being applied'near the free end of the reed has a much greater leverage than the spring contact.

. Due to the fact that the spring contact 58 is prestressed and is not permitted to move intoits relaxed position, the frequency for resonant vibration of the spring contact is very much greater than the resonantfrequency of the'reed.32, and, accordingly, it is not possible for the reed by repeatedly striking the contact 58 to induce chatter or independent vibration of this contact. This provides great reliability of operationin that the spring contact 58 returns to a stable position in the notch 78 in a much shorter time interval than that required for the reed to complete a cycle of its own operation to reengage the contact.

In the illustrated assembly, the reed 32 is connected electrically to the inner frame 26, by virtue of the soldered connection therewith. In turn, the inner frame is connected to the prong 16-b through conductor 88 and one of the springs 24. The contact element 58 is connected electrically to the prong 16-a through another of the springs 24 and a conductor 86 which connects to the rivet 62. Conductor 86 is only partially shown so as not to obscure detail in the drawing. Resonant vibration of the reed 32 may be sensed by an intermittent shorting across the prongs 16-a and 16-h, utilizing conventional circuits devised for this purpose.

Although the preferred embodiment of the device has been described, it will be understood that within the purview of this invention various changes may be made in the form, details, proportion and arrangement of parts, the combination thereof and mode of operation, which generally stated consist in a device capable of carrying out the objects set forth, as disclosed and defined in the appended claims.

Having thus described my invention, I claim:

1. In combination with a vibratile reed element mounted to execute vibratory motion between opposite extremes disposed along a repeated path, a contact assembly for engaging said reed clement adjacent one extreme of said vibratory motion, said contact assembly comprising an elongated resilient contact element, support means fixedly supporting one end of said contact element, said contact element projecting from said support means and terminating at its outer end with a contact portion disposed in said path adjacent said one extreme for engaging said reed upon movement of said reed toward said one extreme, bias means supported fixedly with respect to said support means and having an abutment portion contacting an intermediate portion of said contact element and projecting into the position which would normally be occupied by said intermediate portion in the relaxed state of said contact element, whereby said contact element is displaced from its relaxed state and thereby stressed, the direction of displacement of said contact element being in the direction said reed travels in moving toward said one extreme from its other extreme, whereby said reed, upon engaging said contact portion adjacent said one extreme, exerts a pressure on said contact portion tending to move said contact element away from said abutment and to further stress said contact element.

2. The combination according to claim 1 wherein said abutment portion has a notch therein having walls which diverge from a juncture therebetween in the direction of displacement of said contact element, said notch receiving said contact element between said diverging walls, whereby said contact element in seeking to return to its relaxed state is guided by the walls of said notch to a fixed position adjacent the juncture of said walls.

3. The combination according to claim 1 wherein said bias means comprises an elongated cantilever supported spring element having said abutment portion at the. free end thereof and including adjustable means supported by said support means and engaging said bias .means in spaced relation to said abutment portion, said adjustable means being adjustable so as to vary the position of said abutment portion and thereby vary the position of said contact portion with respect to said one extreme.

4. In combination with a vibratile reed element attached at one end thereofto a supporting frame so asto have the properties of a cantilever. beam, said reed being adapted to execute vibratory motionbetween opposite extremes disposed along a repeated path, a contact assembly for engaging said reed element adjacent one extreme of said vibratory motion, said contact assembly comprising a support plate fixed with respect to said supportin frame-and positioned adjacent said reed but outside its path of vibratory motion, an elongated spring wire contact element, means securing one end of said contact element to said support plate, the free end of said contact element projecting away from said support plate and terminating in a contact portion for engaging said reed, a bias means secured fixedly with respect to said support plate and having an abutment portion engaging said contact element in spaced relation to the contact portion thereof, said abutment portion projecting into the position which would normally be occupied by said contact element in its relaxed state, whereby said contact element is displaced from its relaxed state and thereby stressed, the direction of displacement of said contact element being in the direction said reed travels in moving towards said one extreme from its other extreme, whereby said reed on engaging said contact portion adjacent said one extreme exerts a pressure on said contact portion tending to move said contact element away from said abutment, so as to further stress said contact element.

5. The combination according to claim 4, wherein said bias means comprises an elongated fiat spring element secured at one end to said support plate so as to be mounted as a cantiliver'beam, the longitudinal axis of said fiat spring element being substantially parallel to the longitudinal axis of said reed, said spring element having at the free end thereof an angularly disposed flange directed away from said reed, said flange having a V-shaped notch therein having side walls which are divergent in the direction away from said reed and which are adapted to receive said spring wire contact element therebetween, said flat spring element displacing said spring wire contact away from said reed, whereby the restoring torque in said spring wire contact element presses said contact element into said V-shaped notch and the side walls of said notch guide said spring wire contact into a fixed position at the apex of said notch.

6. The combinationaccording to claim 5 including a screw element threadedly engaged in said support plate and engaged at one end thereof with said cantilever supported flat spring element in spaced relation to the fixed end thereof, said screw element being adjustable with respect to said support plate so as to vary the position of the free end of said cantilever supported flat spring and thereby adjust the displacement of said spring Wire contact element.

7. A contact assembly for engaging a vibratile element comprising a support member, an elongate resilient contact element, means fixedly securing one end of said contact element to said support member, said contact element having an intermediate portion projecting from said support member and terminating in an outer end portion spaced from said support member and adapted to contact said vibratile element, bias means anchored to said support member and having an abutment portion projecting into the position which would normally be occupied by said intermediate portion of said contact element in its relaxed position whereby said contact element is displaced from its relaxed position and thereby stressed, said abutment portion having a notch therein, said notch having side walls diverging from a juncture thereof and receiving said intermediate portion of said contact element therebetween, said side Walls diverging in the direction of displacement of said contact element whereby the restoring torque in said contact element urges said intermediate portion into said notch and the diverging walls of said notch guide said intermediate portion into a fixed position adjacent the juncture therebetween, the construction and arrangement being such that upon said contact assembly being supported adjacent said vibratile element and located with the outer end portion of said contact element in the path of vibratory movement of said vibratile element in such fashion that the displacement of said contact element away from its relaxed position is increased by contact with said vibratileelement, said contact element, yields to vibratory movements of said vibratile element while at the same time said bias means prevents oscil latory movement of said contact element through its relaxed position and thereby prevents resonant vibration of said contact element.

References Cited by the Examiner KATHLEEN H. CLAFFY, Primary Examiner.

BERNARD A. GILHEANY, Examiner. 

1. IN COMBINATION WITH A VIBRATILE REED ELEMENT MOUNTED TO EXECUTE VIBRATORY MOTION BETWEEN OPPOSITE EXTREMES DISPOSED ALONG A REPEATED PATH, A CONTACT ASSEMBLY FOR ENGAGING SAID REED ELEMENT ADJACENT ONE EXTREME OF SAID VIBRATORY MOTION, SAID CONTACT ASSEMBLY COMPRISING AN ELONGATED RESILIENT CONTACT ELEMENT, SUPPORT MEANS FIXEDLY SUPPORTING ONE END OF SAID CONTACT ELEMENT, SAID CONTACT ELEMENT PROJECTING FROM SAID SUPPORT MEANS AND TERMINATING AT ITS OUTER END WITH A CONTACT PORTION DISPOSED IN SAID PATH ADJACENT SAID ONE EXTREME FOR ENGAGING SAID REED UPON MOVEMENT OF SAID REED TOWARD SAID ONE EXTREME, BIAS MEANS SUPPORTED FIXEDLY WITH RESPECT TO SAID SUPPORT MEANS AND HAVING AN ABUTMENT PORTION CONTACTING AN INTERMEDIATE PORTION OF SAID CONTACT ELEMENT AND PROJECTING INTO THE POSITION WHICH WOULD NORMALLY BE OCCUPIED BY SAID INTERMEDIATE PORTIN IN THE RELAXED STATE OF SAID CONTACT ELEMENT, WHEREBY SAID CONTACT ELEMENT IS DISPLACED FROM ITS RELAXED STATE AND THEREBY STRESSED, THE DIRECTION OF DISPLACEMENT OF SAID CONTACT ELEMENT BEING IN THE DIRECTION SAID REED TRAVELS IN MOVING TOWARD SAID ONE EXTREME FROM ITS OTHER EXTREME, WHEREBY SAID REED, UPON ENGAGING SAID CONTACT PORTION ADJACENT SAID ONE EXTREME, EXERTS A PRESSURE ON SAID CONTACT PORTION TENDING TO MOVE SAID CONTACT ELEMENT AWAY FROM SAID ABUTMENT AND TO FURTHER STRESS SAID CONTACT ELEMENT. 